AP500 and its application circuit (ab)

AP500 is a high-performance two-channel FET DC power amplifier driver module. It uses a higher operating voltage.
With high driving power, low distortion, wide frequency response and simple peripheral circuit, it has incomparable advantages when used in audio circuits
. 
    AP500 can output a large driving power, and its performance is very good. Using this circuit, you can easily create
a high-power amplifier circuit.
    AP500 adopts a pure DC structure internally, and the output zero-point potential is quite stable. Within the operating voltage
range of ±14 to ±60V, the output zero-point drift is less than 90mV. Its output is equipped with a protection circuit, which
will not damage the module even if the power amplifier tube it is connected to is short-circuited. AP500 has excellent low-frequency characteristics, and the gain can still reach 27dB during DC amplification.
Such excellent low-frequency characteristics are of great significance for improving the transient indicators of the power amplifier circuit and reducing distortion. The circuit's
ultimate operating voltage reaches ±75V, which not only provides a larger output signal voltage, but also improves the dynamic characteristics of the circuit
. Since the internal circuit is a DC structure, its input and output can be directly coupled. In the application of power amplifier circuits
, AP500 can produce power
amplifier circuits with various characteristics such as OTLOCL, II II, BTL, Class A and B, Super Class A, Class A, etc. Due to the low power consumption of this module, there is no need to install a radiator during use.
    The module is also equipped with an automatic zero-sum distortion correction circuit inside the module. Its distortion is ≤0.02%, the conversion rate is as high as
70V/r./S, and the closed-loop operating frequency response is 0~500kHz.
    The AP500 module uses a single in-line plug-in l5 pin The package, appearance and pin arrangement are shown in Figure 2-128 (a). The pin
functions are: pin 1 is connected to the negative power supply; pin 23 is the static bias adjustment terminal of the L channel; pins 4 and 5 are the L channel The signal output terminal;
pin 6 is the negative feedback terminal of the L channel; pin 7 is the signal input terminal of the L channel; pin 8 is the ground terminal; pin 9 is
the signal ; pin 10 is the R channel signal input terminal. It is the negative feedback terminal; pins 11 and 12 are the R channel signal output terminals; pins 13 and 14 are
the static bias adjustment terminals of the R channel; pin 15 is connected to the positive power supply.
    Figure 2-12,8 (b) is its application circuit . This circuit uses AP500 to directly drive a pair of composite tubes for complementary symmetrical push-pull
output. Under the power supply voltage of ±28V, the maximum output power can reach 90W
. If the working voltage is increased and high-power output tubes are used, the maximum output power can reach 200W. The circuit can work without debugging. If there are requirements for the quiescent current of the power amplifier tube
, an adjustable resistor can be connected to pins 2 and 3 of the AP500 (pins 13 and 14 of the other channel) to adjust the set
quiescent . Generally, the output tube The quiescent current can be adjusted to about 40mA to achieve good working status.